If you honestly think she understands she got played and that you were protecting her then start drafting a letter.
You don't be mean, you tell her how much harm lying and sneaking around does. You tell her if this marriage ENDS you want it CIVIL and THAT is something you BOTH deserve.
You tell her the marriage isn't what you are after, its RESPECT. you tell her despite the state of the marriage she has no right be belittle your dignity like that.
You tell her DESPITE how HORRIBLE she's been YOU tried to PROTECT her and SAVE the marriage's DIGNITY instead.
You tell her she can hate you all she wants to, but you are going to be civil and you did your best to protect her from getting used. You tell her she may want a divorce but there's a right way and a wrong way to carry that out.
